Hyperspectral photoluminescence imaging as a tool to study defects in silicon solar cell materials (Conference Presentation)

Hyperspectral imaging in the SWIR wavelength region (1000 nm – 2500 nm) makes it possible to map mechanisms for recombination of photogenerated charge carriers in semiconductors. These mechanisms are linked to imperfections and impurities and lead to decreased performance in solar cells. The hyperspectral camera is mounted with a line laser at wavelength 808 nm, an energy high enough to excite electrons from the valence band to the conduction band in the Silicon material. The camera records radiative photoluminescence from the material, both the Silicon band to band recombination as well as recombinations from trapped electrons due to imperfections. In combination with advanced multivariate techniques for data analysis, this technology have been used to study defects in both multicrystalline and monocrystalline wafers and solar cells. Some of the mapped defects have been linked to well known mechanisms that could previously only be studied by destructive and time consuming methods. So far this technique has only been explored in research laboratories. The goal is however to be able to use this in line in solar cell processing. In this presentation it will also be discussed how this technology can be used to map degradation of outdoor solar panels.